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Occult Blood Colorectal carcinoma is the second leading cause of cancer deaths in the United States. Approximately 150,000 individuals are diagnosed each year. About a third of these patients will die of the disease. The good news is that survival rates increase dramatically if the cancer is detected and treated early, while the lesion remains localized.Screening Methods Abundant evidence suggests that premalignant or adenomatous polyps are precursors to colorectal cancer. Since both polyps and colorectal carcinomas bleed intermittently, detection of this small, hidden amount of blood in the stool is an easy and inexpensive screening tool. Fecal occult blood tests (FOBT) are based on the oxidation reaction of the guaiac reaction in the presence of hemoglobin. The oxidation results in a quinone compound that turns the test card blue. Since fruits and vegetables contain peroxidases that also cause oxidation, they will react like hemoglobin (if their reactivity is high or quantity is sufficient) and cause a false positive using most FOBT methods. These methods require patients to observe the following dietary restrictions for at least 48 hours before and through the test period: Foods to Eat ˇ Well-cooked pork, poultry and fish ˇ Any cooked fruits and vegetables ˇ High fiber foods, e.g. whole wheat bread, bran cereal, popcorn Foods and Drugs to Avoid ˇ Red meat (beef, lamb), including processed meats and liver ˇ Raw fruits and vegetables, especially melons, radishes, turnips and horseradish ˇ Aspirin or other non-steroidal anti-inflammatory drugs, for 7 days prior to and during the testing period ˇ Vitamin C in excess of 250 mg a day The American Cancer Society recommends annual FOBT on three consecutive bowel movements for individuals over 40 years old. The digital rectal exam (DRE) detects up to 15% of colorectal cancers, those in the rectal area. The American Cancer Society recommends an annual DRE for persons over 40 years old. Endoscopy is a more invasive and more costly screening method, but it allows visualization of the lower portion of the descending colon, the site of 50 - 60% of all colorectal cancers. Small tissue samples and/or polyps can be removed during this procedure for biopsy. The American Cancer Society recommends proctosigmoidoscopy every 3-5 years for persons over 50. An air contrast barium enema is a follow-up test for symptomatic individuals. Although not 100% accurate, it often detects small lesions and polyps missed by endoscopic examination. Risk Factors Individuals over 40 are at greater risk for colorectal carcinoma, as are those with low fiber/high fat diets. A family history of colorectal cancer, polyps or familial polyps places one at greater risk. A personal history of inflammatory bowel disease, polyps, Turcot Syndrome, Crohn's Colitis, Gardner's Syndrome or Peutz-Jeghers Syndrome also increases the risk. |
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This article may be republished in its entirety on your web site or in your newsletter under the following two conditions: 1) Include the following statement at the beginning or end of the article. "Republished with permission of the author, Margaret A Knapp MT(ASCP) CLS, of KnappˇFrazer Consulting. www.knapp-frazer.com ~ 707.539.6621" 2) Send copy of your publication or URL to KnappˇFrazer Consulting at time of republication. |
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